Oxidative dehydrogenation process



United States Patent 3,308,188 OXIDATIV E DEHYDROGENATION PROCESSLairnonis Bajars, Princeton, N..l., assignor to Petro-Tex ChemicalCorporation, Houston, Tex., a corporation of Delaware No Drawing. FiledOct. 22, 1965, Ser. No. 502,490 14 Claims. (Cl. 260-680) Thisapplication is a continuation-in-part of my earlier filed pendingapplication Serial Number 250,019 filed January 8, 1963, entitled,Process of Dehydrogenation, now abandoned, which in turn was acontinuationin-part of my now abandoned applications Serial Number52,766 filed August 30, 1960, entitled, Improved DehydrogenationProcess, Serial Number 145,992 filed October 18, 1961, entitled,Dehydrogenation of Hydrocarbons, Serial Number 145,993 filed October 18,1961, entitled, Dehydrogenation Process, Serial Number 156,955 filedDecember 4, 1961, entitled, Process of Dehydrogenation, Serial Number156,957 filed December 4, 1961, entitled, Dehydrogenation Method, andSerial Number 207,105 filed July 2, 1962, entitled, ImprovedDehydrogenation Process.

This invention relates to a process for dehydrogenating organiccompounds and relates more particularly to the dehydrogenation oforganic compounds in the vapor phase at elevated temperatures in thepresence of oxygen, bromine and an improved inorganic contact mass.

It has been found recently that a great variety of dehydrogenatableorganic compounds may be dehydrogenated by reacting a mixture of anorganic compound containing at least one pair of adjacent carbon atoms,each of which possess at least one hydrogen atom, bromine or abromine-liberating material, and oxygen under specified conditions at anelevated temperature, and at a reduced partial pressure of the organiccompound, in the presence of certain metals or compounds thereof toobtain the corresponding unsaturated organic compound containing atleast one I have found, quite unexpectedly, that this process may beimproved so that increased selectivities and yields of unsaturatedorganic compound derivatives containing the grouping are obtained moreefficiently even with less bromine and under less stringent processconditions, e.g. at lower temperatures, when such reaction is conductedin the presence of a contact mass comprising as a first com ponent atleast one element of a metal of Groups Ia and lIa (i.e. the alkali andalkaline earth metals) together with a second component which is amember selected from the group consisting of metals and compoundsthereof of Periodic Table 1 Group VIIIb.

The process of this invention can be applied to a great variety oforganic compounds to obtain the corresponding unsaturated derivativethereof. Such compounds normally will contain from 2 to 20 carbon atoms,at least one HH II (llglslgge Chemistry, 3rd edition(Appleton-Century-Crofts, Inc.,

below about 350 C. Such compounds may contain in addition to carbon andhydrogen, oxygen, halogens, nitrogen and sulphur. Among the classes oforganic compounds which are dehydrogenated by means of the novel processof this invention are alkancs, alkenes, alkyl halides, ethers, esters,aldehydes, ketones, organic acids, alkyl aromatic compounds, alkylheterocyclic compounds, cyanoalkanes, cycloalkanes and the like.Illustrative dehydrogenation include ethylbenzene to styrene,isopropylbenzene to a-methyl styrene, ethylcyclohexane to styrene,cyclohexane to benzene, ethane to ethylene and acetylene, ethylene toacetylene, propane to propylene, isobutane to isobutylene, n-butane tobutene and butadiene-l,3, butene-1 to butadiene-1,3 and vinyl acetylene,cis or trans butene-2 to butadiene-l,3, butane or butene to vinylacetylene, butadiene-l,3 to vinyl acetylene, methyl butene to isoprene,isobutane to isobutylene, propionaldehyde to acrolein, ethyl chloride tovinyl chloride, propionitrile to acrylonitrile, methyl isobutyrate tomethyl methacrylate, and the like. Other representative materials whichare readily dehydrogenated in the novel process of this inventioninclude ethyl toluene, the alkyl chlorobenzenes, ethyl naphthalene,isobutyronitrile, propyl chloride, isobutyl chloride, ethyl fluoride,ethyl dichloride, butyl chloride, the chlorofluoroethanes, methylethylketone, diethyl ketone, methyl propionate, and the like. This inventionis useful in the preparation of vinylidene compounds containing at leastone CH =C group, that is, a compound possessing at least one groupcontaining a terminal methylene group attached by a double bond to acarbon atom, and 2 to 12 carbon atoms and is particularly useful in thedehydrogenation of hydrocarbons containing 2 to 5 carbon atoms oraliphatic nitriles of 3 to 4 carbon atoms. Preferred compounds to bedehydrogenated are hydrocarbons of 4 to 8 carbon atoms having at leastfour contigous non-quaternary carbon atoms. Aliphatic acyclichydrocarbons of from 4 to 5 or 6 carbon atoms are preferred. Theinvention is further particularly adapted to provide butadiene-1,3 frombutane and butene and isoprene from isopentane and isopentene in highyields and excellent conversion and selectivity.

As shown by the examples below and the disclosures herein, the novelprocess of this invention is applicable to a great variety of organiccompounds containing 2 to 20 carbon atoms and at least one pair ofadjacent carbon atoms bonded together and each carbon atom possessing atleast one hydrogen atom including the following: hydrocarbons includingboth alkanes and alkenes, especially those containing 2 to 6 or 8carbons; carbocyclic compounds containing 6 to 12 carbon atoms,including both alicyclic compounds and aromatic compounds of the formulawherein Ar is phenyl or naphthyl, R is hydrogen or methyl and X and Yare hydrogen or alkyl radicals containing 1 to 4 carbon atoms, orhalogen; alkyl ketones containing 4 to 6 carbon atoms; aliphaticaldehydes containing 3 to 6 carbon atoms; cyanoalkanes containing 2 to 6carbon atoms; halo-alkanes and halo-alkenes containing 2 to 6 carbonatoms, particularly chloroand fluoro-alkanes and the like. Vinylidenecompounds containing the CH =C group, that is, containing a terminalmethylene group attached by a double bond to a carbon atom, are readilyobtained from organic compounds containing 2 to 12 carbon atoms and atleast one group wherein adjacent carbon atoms are singly bonded andpossess at least one hydrogen each. For example, vinylidene halides;vinyl esters; acrylic acid and alkyland halo-acrylic acids and esters;vinyl aromatic compounds; vinyl ketones; vinyl heterocyclic compounds;diolefins containing 4 to 6 carbon atoms, olefins containing 2 to 8carbon atoms, and the like are obtained as products. The vinylidenecompounds normally contain from 2 to 12 carbon atoms and are well knownas a commercially useful class of materials for making valuable polymersand copolymers therefrom.

Useful feeds as starting materials may be mixed hydrocarbon streams suchas refinery streams. For example, the feed material may be theolefin-containing hydrocarbon mixture obtained as the product from thedehydrogenation of hydrocarbons. Another source of feed for the presentprocess is from refinery by-products. Although various mixtures ofhydrocarbons are useful, the preferred hydrocarbon feed contains atleast 50 weight percent butene-1, butene-2, n-butane and/or butadiene-1,3 and mixtures thereof, and more preferably contains at least 70percent n-butane, butene-1, butene-2 and/or butadiene-l,3 and mixturesthereof. Any remainder usually will be aliphatic hydrocarbons. Theprocess of this invention is particularly effective in dehydrogenatingacyclic aliphatic hydrocarbons to provide a hydrocarbon product whereinthe major unsaturated product has the same number of carbon atoms as thefeed hydrocarbon.

Bromine may be employed as free bromine or as any bromine-containingmaterial which liberates the specified amount of free bromine under theconditions of reaction as defined hereinafter. For example, bromine,hydrogen bromide, the alkyl bromides, such as methyl bromide and ethylbromide, wherein the alkyl groups preferably contain 1 to 6 carbonatoms; ammonium bromide and the like. Additional bromine compounds arebromohydrins such as ethylene bromohydrin; bromo substituted aliphaticacids such as bromoacetic acid; organic amine bromide salts such asmethyl amine hydrobromide; and other bromide compounds such as SBr CHBrCBr and the like. Generally, the bromine compound will have a boiling ordecomposition point of less than 400 C. and usually no greater than 100C. Preferred are ammonium bromide, molecular or elemental bromine and/orhydrogen bromide. It is an advantage of this invention that hydrogenbromide or ammonium bromide may be employed as the bromine source, withone advantage being that the hydrogen bromide or ammonium bromide in theeffluent from the reactor may be fed directly back to contact thehydrocarbons in the dehydrogenation reactor without any necessity ofconverting the hydrogen bromide to bromine. It is understood that when aquantity of bromine is referred to herein, both the specification andthe claims, that this refers to the calculated quantity of bromine inall forms present in the vapor space under the conditions of reactionregardless of the initial source or the form in which the bromine ispresent. For example, a reference to 0.05 mol of bromine would refer tothe quantity of bromine present whether the bromine was fed as 0.05 molof Br or 0.10 mole of HBr.

The amount of bromine usually will be in an amount greater than about0.0001 mol of bromine, such as at least 0.001 mol, or the equivalentamount of bromineliberating material per mol of organic compound to bedehydrogenated, more usually at least about 0.01 mol equivalent ofbromine per mol of organic compound will be employed. Large amounts ofbromine may be used, as high as one-half to one mol or more per mol oforganic compound to be dehydrogenated, but it is one of the unexpectedadvantages of this invention that only very small amounts of halogen arerequired, normally less than about 0.2 mol total equivalent of bromineand more desirably less than 0.1 mol of bromine per mol of organiccompound to be dehydrogenated. Amounts of bromine between 0.001 or 0.005and 0.08 or 0.09 mole of bromine per mol of the organic compound to bedehydrogenated are preferred, with the range of about 0.01 to 0.05 beingparticularly preferred. Preferably the bromine will be present in anamount no greater than 5 or 10 mol percent of the total feed to thedehydrogenation zone.

The amount of oxygen employed will normally be at least about one-fourthmol of oxygen per mol of organic compound to be dehydrogenated.Generally greater than 0.25 mols of oxygen per mol of the organiccompound will be used. Excellent yields of the desired unsaturatedderivatives have been obtained with amounts of oxygen from about 0.4 toabout 1.5 mols of oxygen per mol of organic compound, and within therange of about 0.25 or 0.4 to 2 mols of oxygen per mol of organiccompound economic, production and process considerations will dictatemore exactly the normal ratio of oxygen to be used. A preferred range ofoxygen is from 0.5 to 1.2 mols of oxygen per mol of compound to bedehydrogenated. Large amounts of oxygen may be used with short contacttime and high dilutions as with steam, for example, 30 to 50 moles permol of organic compound. Oxygen is supplied to the reaction system aspure oxygen, or as oxygen diluted with inert gases such as helium,carbon dioxide or as air and the like. In relation to bromine, excellentresults are obtained when the amount of oxygen employed is greater thanone mol, as 1.25, of oxygen per atom of bromine present in the reactionmixture, usually greater than about 1.5 moles of oxygen per atom ofbromine. Usually the ratio of the mols of oxygen to the mols of brominewill be at least 3 such as from 5 or 8 to 500 and preferably will bebetween 15 and 300 mols ofoxygen per mol of bromine.

While the total pressure on systems employing the process of thisinvention normally will be at on in excess of atmospheric pressure,vacuum may be used. Higher pressures, such as about or 200 p.s.i.g. maybe used. The partial pressure of the organic compound under reactionconditions usually will be equivalent to below 10 inches mercuryabsolute when the total pressure is atmospheric. Better results andhigher yields of desired product are normally obtained when the partialpressure of the organic compound is equivalent to less than aboutone-third or one-fifth of the total pressure. Also because the initialpartial pressure of the hydrocarbon to be dehydrogenated is generallyequivalent to less than about 10 inches of mercury at a total pressureof one atmosphere, the combined partial pressure of the hydrocarbon tobe dehydrogenated plus the dehydrogenated hydrocarbon will also beequivalent to less than about 10 inches of mercury. For example, underthese conditions, if butene is being dehydrogenated to butadiene, at notime will be combined partial pressure of the butene and 'butadiene begreater than equivalent to about 10 inches of mercury at a totalpressure of one atmosphere. Preferably the hydrocarbon to bedehydrogenated should be maintained at a partial pressure equivalent toless than one-third the total pressure, such as no greater than sixinches or no greater than four inches of mercury, at a total pressure ofone atmosphere. The desired pressure is obtained and maintained bytechniques including vacuum operations, or by using helium, organiccompounds, nitrogen, steam and the like, or by a combination of thesemethods. Steam is particularly advantageous and it is surprising thatthe desired reactions to produce high yields of product are effected inthe presence of large amounts of steam. Steam is particularlyadvantageous to obtain the required low partial pressure of the organiccompound in the process. When steam is employed, the ratio of steam toorganic compound is normally above about two mols of steam per mol oforganic compound such as within the range of about 2; or 5 to 20 or 30mols, although larger amounts of steam as high as 40 mols have beenemployed. The degree of dilution of the reactants with steam and thelike is. related to maintaining the partial pressure of the organiccompound in the system at below about one-third atmosphere andpreferably below inches mercury absolute when the total pressure on thesystem is one atmosphere. For example, in a mixture of one mol ofbutene, three mols of steam and one mol of oxygen under a total pressureof one atmosphere the butene would have an absolute pressure ofone-fifth of the total pressure, or roughly six inches of mercuryabsolute pressure. Equivalent to this six inches of mercury buteneabsolute pressure at atomspheric pressure would be butene mixed withoxygen and bromine under a vacuum such that the partial pressure of thebutene is six inches of mercury absolute. A combination of a diluentsuch as steam together with a vacuum may be utilized to achieve thedesired partial pressure of the hydrocarbon. For the purpose of thisinvention, also equivalent to the six inches of mercury butene absolutepressure at atomspheric pressure would be the same mixture of one mol ofbutene, three mols of steam and one mol of oxygen under a total pressuregreater than atmospheric, for example, a total pressure of or inchesmercury above atmospheric. Thus, when the total pressure on the reactionzone is greater than one atmosphere, the absolute values for thepressure of butene will be increased in direct proportion to theincrease in total pressure above one atmosphere. Another feature of thisinvention is that the combined partial pressure of the hydrocarbon to bedehydrogenated plus the bromine-liberating material will preferably alsobe equivalent to less than 10 inches of mercury, and preferably lessthan 6 or 4 inches of mercury, at a total pressure of one atmosphere.The lower limit of organic compound partial pressure will be dictated bycommercial considerations and normally will be greater than about 0.1inch of mercury absolute.

The temperature of the reaction is from above 400 C. to about 800 C. or1000 C. Preferably the temperatures will be from at least 450 C. to 900C., and generally will be at least about 500 C. The optimum temperaturemay be determined as by thermocouple at the maximum temperature of thereaction. Usually the temperature of reaction will be controlled betweenabout 450 C. and about 750 C. or 800 C.

The flow rates of the gaseous reactants may be varied quite widely andgood results have been obtained with organic compound gaseous flow ratesranging from about 0.25 to about 3 liquid volumes of organic compoundper volume of reactor packing per hour, the residence or contact time ofthe reactions in the reaction zone under any given set of reactionconditions depending upon the factors involved in the reaction.Generally, the flow rates will be within the range of about 0.10 to orhigher liquid volumes of the hydrocarbon to be dehydrogenated,calculated at standard conditions of 0 C. and 760 mm. of mercury pervolume of reactor space containing catalyst per hour (referred to aseither LHSV or liquid v./v./hr.). Usually the LHSV will be between 0.15and 15. The volume of reactor containing catalyst is that volume ofreactor space including the volume displaced by the catalyst. Forexample, if a reactor has a particular volume of cubic feet of voidspace, when that void space is filled with catalyst particles theoriginal void space is that volume of reactor containing catalyst forthe purpose of calculating the flow rates. The resideuce or contact timeof the reactants in the reaction zone under any given set of reactionconditions depends upon all the factors involved in the reaction.Contact times ranging from about 0.01 to about two seconds at about 450C. to 750 C. have been used. A wider range of residence times may beemployed, as 0.001 second to about 10 or 15 seconds. Residence time isthe calculated dwell time of the reaction mixture in the reaction zoneassuming the mols of product mixture are equivalent to the mols of feedmixture.

For conducting the reaction, a variety of reactor types may be employed.Fixed bed reactors may be used and fluid and moving bed systems areadvantageously applied to the process of this invention. In any of thereactors suitable means for heat removal may be provided. Tubularreactors of large diameter Which are loaded or packed with the solidcontact mass are satisfactory.

Good results have been obtained when the exposed surface of the solidcontact mass is greater than about 25 square feet, preferably greaterthan about 50 square feet per cubic foot of reactor as 75 or or higher.Of course, the amount of catalyst surface may be much greater whenirregular surface catalysts are used. When the catalyst is in the formof particles, either supported or unsupported, the amount of catalystsurface may be expressed in terms of the surface area per unit weight ofany particular volume of catalyst particles. The ratio of catalyticsurface to weight will be dependent upon various factors including theparticle size, particle distribution, apparent bulk density of thecarrier, and so forth. Typical values for the surface to Weight ratioare such as about /2 to 200 square meters per gram, although higher andlower values may be used.

Excellent results have been obtained by packing the reactor withcatalyst particles as the method of introducing the catalytic surface.The size of the catalyst particles may vary widely but generally themaximum particles size will at least pass through a Tyler StandardScreen which has an opening of 2 inches, and generally the largestparticles of catalyst will pass through a Tyler Screen with one inchopenings. Thus, the particle size when particles are used preferablywill be from about 10 microns to a particle size which will pass througha Tyler Screen with openings of 2 inches. If a carrier is used thecatalyst may be deposited on the carrier by methods known in the artsuch as by preparing an aqueous solution or dispersion of the catalyst,mixing the car rier with the solution or dispersion until the activeingredients are coated on the carrier. The coated particles may then bedried, for example, in an oven at about C. Various other methods ofcatalyst preparations known to those skilled in the art may be used.Very useful carriers are the Alundums, silicon carbide, theCarborundums, pumice, kieselguhr, asbestos, and the like. When carriersare used, the amount of catalyst composition on the carrier willgenerally be in the range of about 2 to 80 weight percent of the totalweight of the active catalytic material plus carrier. Another method forintroducing the required surface is to utilize as a reactor a smalldiameter tube wherein the tube wall is catalytic or is coated withcatalytic material. If the tube wall is the only source of catalystgenerally the tube will be of an internal diameter of no greater thanone inch such as less than inch in diameter or preferably will be nogreater than about /2 inch in diameter. The technique of utilizing fluidbeds lends itself well to the process of this invention,

In the above descriptions of catalyst compositions, the compositiondescribed is that of the surface which is exposed in the dehydrogenationzone to the reactants. That is, if a catalyst carrier is used, thecomposition described as the catalyst refers to the composition of thesurface and not to the total composition of the surface coating pluscarrier. The catalytic compositions are intimate combinations ormixtures of the ingredients. 'Ihese ingredients may or may not bepresent as alloys. Catalyst bindingagents or fillers may be used, butthese will not ordinarily exceed about 50 percent or 65 percent byweight of the catalytic surface. The defined catalytic components willbe the main active constituents in the catalyst and the catalyst mayconsist essentially of the defined catalytic components. The weightpercent of the defined catalytic atoms will generally be at least 20 2As measured by the Innes nitrogen absorption method on a representativeunit volume of catalyst particles. The Innes is reported in Innes, W,B., Anal. Chem, 23, 759

percent, and are preferably at least 35 percent of the composition ofthe catalyst surface exposed to the reaction gases and will generally beat least 51 or about 80 atomic Weight percent of any cations in thesurface, such as at least 80 atomic percent of any metal cations in thesurface.

The defined catalyst combinations may be employed in any form, e.g., aspellets, tablets, as coatings on carriers or supports, and the like, inboth fixed and fluidized beds. Other methods of catalyst preparationknown to those skilled in the art may also be used.

According to this invention, the catalyst is autoregenerative and thusthe process is continuous. Little or no energy input is required for theprocess and it may be operated essentially adiabatically. Moreover,small amounts of tars and polymers are formed as compared to prior artprocesses. It is also an advantage of this invention that triple bondcontaining compounds are more easily obtained than with catalystscontaining only one of the defined components.

In the examples given below the conversions, selectivities and yieldsare expressed as mol percent based on the mols of the compound to bedehydrogenated fed to the reactor. The temperature of reaction listed isapproximately the maximum temperature in the reactor. The catalysts arepresent as fixed beds.

The Group Ia and 11a compounds used include, for example, oxides,hydroxides and salts such as the phosphates, sulfates, halides and thelike. Useful compounds include, for example, lithium chloride, lithiumOxide, lithium bromide, lithium fluoride, lithium phosphate, sodiumhydroxide, sodium oxide, sodium chloride, sodium sulfate, berylliumoxide, sodium bromide, sodium iodide, sodium phosphate, sodium fluoride,potassium chloride, potassium bromide, potassium sulfate, potassiumiodide, potassium nitrate, potassium citrate, potassium hydroxide,potassium oxide, potassium phosphate, rubidium chloride, rubidiumbromide, rubidium iodide, rubidium oxide, magnesium acetate, magnesiumbromide, magnesium oxide, magnesium iodide, calcium oxide, calciumacetate, calcium oxalate, calcium chloride, calcium bromide, calciumiodide, calcium phosphate, calcium fluoride, strontium oxide, strontiumhydroxide, strontium chloride, strontium bromide, barium oxide, bariumchloride, barium hydroxide, barium sulfate, barium bromide, bariumiodide, beryllium chloride, and the like, and mixtures thereof.Preferred Group Ia and Ha metal elements are lithium, sodium, magnesium,potassium, calcium, strontium and barium, such as the oxides,phosphates, iodides, bromides, chlorides or fluorides of these metals.The oxides and halides and mixtures thereof are particularly preferred.Many of the Group Ia and Ila compounds may change during the preparationof the catalyst, during heating in a reactor prior to use in the processof this invention, or are converted to another form under the describedreaction conditions, but such materials still function as an effectivecompound in the defined process. For example, the halides may beconverted to the oxides or vice versa under the conditions of reaction.The amount of Group Ia metal compound or Group IIa metal compound withthe additional metal or inorganic compound thereof may be varied quitewidely and While small amounts, as low as one-tenth percent based on thetotal catalyst, have been used, much larger amounts may be employed inconcentrations up to where Group Ia or Ha metal compound is the largerconstituent in the composition, such as up to 50 weight percent or more,as 95 percent. Normally up to 50 percent, and more usually about one toabout twenty-five percent of the Group Ia or Group IIa compound, such asabout one to ten percent, with the remainder being the defined secondinorganic metal compound, is satisfactory. On an atomic basis, thecombined amount of the metal atoms of Group Ia and/ or Ha will be fromat least about 0.001 atoms per atom of the defined second catalystcomponent and mixtures thereof. Excellent results are obtained at ratiosof about 0.01 to 1.0 or 1.5 atoms of Group In and Ha per atom of theelements from the second specified group, such as from about 0.01 or0.02 to 0.5 atoms of Group Ia and 11a per atom of the elements from thesecond specified group.

A variety of metals or metal compounds of Periodic Table Group VIIIb maybe used as the second component in conjunction with the Group Ia and 11ametal compounds. Metals of the described second component group inelemental form may be employed and are included within the scope of thisinvention. The metals generally are changed to inorganic compoundsthereof, at least on the surface, under the reaction conditions setforth herein. Particularly effective are inorganic compounds such as theoxides and salts including the phosphates and the halides, such as theiodides, bromides, chlorides and fluorides. Inorganic compounds whichare useful as the second component in the compounded contact mass forthe process of this invention include palladium oxide, ferric oxide,ferrous oxide, iron phosphate, iron phosphide, nickel oxide, ironcarbonate, iron sulfate, cobalt nitrate, cobaltous oxide, cobalticoxide, ferric phosphate, ferrous chloride, and the like. Preferably thecatalyst will be solid under the conditions of reaction. Excellentcatalysts are those comprising atoms of iron, cobalt, nickel andpalladium, such as the oxides, phosphates, iodides, bromides, chloridesor fluorides of these elements. Many of the salts, oxides and hydroxidesof the metals of the listed groups may change during the preparation ofthe catalyst, during heating in a reactor prior to use in the process ofthis invention, or are converted to another form under the describedreaction conditions, but such materials still function as an effectivecompound in the defined process. For example, many of the metalnitrates, nitrites, carbonates, hydroxides, acetates, and the like maybe converted to the corresponding oxide or bromide under the reactionconditions defined herein. Salts which are stable or partially stable atthe defined reaction temperatures are likewise effective under theconditions of the described reaction, as well as such compounds whichare converted to another form in the reactor. At any rate, the catalystsare effective if the defined catalyst is present in a catalytic amountin contact with the reaction gases. Useful catalyst combinations includeiron oxide and lithium chloride, iron oxide and calcium chloride,ferrous chloride and potassium chloride, ferrous chloride and rubidiumchloride, ferrous chloride and lithium hydroxide, iron oxide and lithiumhydroxide, ferrous sulfate and potassium sulfate, ferric oxide pluslithium oxide and barium oxide, ferric oxide, lithium chloride andbarium hydroxide, cobalt chloride and calcium chloride and the like. InGroup VIIIb the preferred elements are those in the fourth period, i.e.,iron, cobalt and nickel. Iron is particularly preferred and superiorresults have been obtained with iron.

In Examples 1 to 6 tubular Vycor 3 reactor, containing the describedsolid contact masses, equipped with an external electric furnace isused. The reaction conditions and the active materials used are setforth in the specific examples. The organic compound and oxygen areadded at the top of the reactor, the bromine material is added to thisstream as it enters the reactor and steam is added separately oppositethis stream. The results are reported as mol percent conversion,selectivity and yield of desired unsaturated product per pass.

Example 1 N.Y., and is composed of approximately 96 percent silica withthe remainder belng essentially B203.

hydrogenated in this example. n-Butane, steam and oxygen in a molarratio of 15 mols of steam and 1.0 mol of oxygen per mol of n-butane arefed to the reactor at a n-butane flow rate of 0.11 liter per minute STP,equivalent to a flow rate of /2 liquid v./v./hr. Aqueous hydrogenbromide is added in a molar ratio of 0.056 mol per mol of n-butane.n-Butane is converted to butadiene-1,3 at 600 C. at a conversion of 66percent and selectivity of 63 percent for a yield of 42 percent perpass.

Example 2 Another contact mass is prepared by evaporating an aqueousdispersion containing Fe O and CaO onto 4 to 8 mesh Alundum granules.The coated particles contain about 90 percent Fe O and 10 percent CaO.The Vycor reactor is loaded with this contact mass and butene-Z, steam,oxygen, and hydrogen bromide as an aqueous 48 percent solution are fedinto the reactor at a flow rate of butene-2 of 1 liquid v./v./hr. overan eight inch deep catalyst bed. The molar ratio of reactants is one molof butene-2, 12.5 mols of steam, 0.7 mol of oxygen, and 0.01 mol of BrAt 615 C. a yield of 85 percent butadiene-l,3 per pass is obtained at aconversion of 90 percent and selectivity of 95 percent. With 0.02 mol ofBr per mol of butene-2 at 580 C., a yield of butadiene-1,3 of 89 percentat a conversion of 92 percent and selectivity of 97 percent is obtained.

Example 3 Iron oxide is deposited by evaporation on 6 mm. Vycor Raschigrings from a water slurry thereof which contains 2.5 percent lithiumhydroxide, based on the iron oxide, and the coated rings are air dried.Butene-2, oxygen, steam, and hydrogen bromide as an aqueous 48 percentsolution are fed into the Vycor reactor containing the coated rings at aflow rate of one-half liquid v./v./hr. of butene-Z in a molar ratio ofone mol of butene-2, 0.35 mol of oxygen, 15 mols of steam and 0.028 molof Br at 550 C. The yield of butadiene-1,3 per pass for the ironoxide-lithium hydroxide contact mass is 76 percent at a conversion of 92percent and selectivity of 83 percent.

When Example 3 is repeated with the exception that the Vycor Raschigrings had coated thereon lithium hydroxide or iron oxide only, the yieldof butadiene-1,3

was less than that obtained from the mixed catalyst. An unexpectedsynergistic effect is involved since use of an active surface containingonly iron oxide or lithium hydroxide resulted in yields of much lessthan that obtained when the two were used together.

Example 4 A mixture of 90 percent Fe O and 10 percent barium oxide isdeposited on 4 to 8 mesh Alundum chips from an aqueous dispersion. Thecoated pellets are air dried and placed in a reactor. Butene-2 isdehydrogenated over this contact mass at a flow rate of one v./v./hr. ofbutene-2 at 1100 F. and with a ratio of reactants of one mol of butene,0.03 mol of Br supplied as a 30 percent aqueous solution of ammoniumbromide, 0.8 mol of oxygen supplied as air, and 12 mols of steam. Ayield of 86 percent butadiene-l,3 per pass is obtained over this contactmass at a conversion of 91 percent and selectivity of 95 percent.

When the examples above are repeated with other contact masses such asmixtures of iron sulfate and calcium oxide; ferric oxide and lithiumoxide; good yields of butadiene-1,3 are obtained from butene.

Example Isopentane is dehydrogenated over a solid contact masscomprising 80 percent ferrous chloride, percent lithium chloride, and 10percent calcium chloride, at a flow rate of isopentane of one-halfliquid v./v./hr. in a molar ratio of one mol of isopentane, 15 mols ofsteam, 1.5 mols of oxygen and 0.11 mol of bromine (as 48 percenthydrobromic acid) at a temperature of 525 C. The selectivity to pentenesis 16 percent and to isoprene 49 percent for a total selectivity of 65mol percent.

Example 6 Example 7 Another demonstration of the value of the contactmasses of this invention is shown by a contact mass prepared in the sameway as described above with 84.5 percent cobalt chloride and 15.5 ercentcalcium chloride, under the same reaction conditions (12.5 steam and 0.7oxygen per mol of butene) at 577 C. and witlr0.-005 mol of bromine. Ayield of 54 percent butadiene-1,3 per pass was obtained from butene at aconversion of 62 percent and selectivity of 88 percent.

Example 8 Isopentane is dehydrogenated to isoprene and amylenes bypassing it through a catalyst bed of 90 weight percent Fe O and 10weight percent LiOH. The temperature is 525 C., the flow rate is 0.5LHSV and the ratios of reactants are 0.11 mols bromine, 15 mols steamand 1.5 mols of oxygen per mol of isopentane. The selectivity is 76percent.

Example 9 Example 8 is repeated substituting a catalyst of 80% FeCl and20% KCl and by using a temperature of 500 C. The selectivity is 76percent.

Example 10 Ethyl benzene is dehydrogenated to styrene in a one inchinternal diameter Vycor reactor according to the general procedure usedabove. The flow rate of ethylbenzene is 0.5 LHSV, the mol ratio ofoxygen to ethylbenzene is 1.0 and 10 mols of steam are used per mol ofethyl benzene. Hydrogen bromide solution was added at a rate equivalentto 0.07 mol of -Br per mol of ethylbenzene. The catalyst is percent byweight Fe O and 10 percent CaO on a carrier. At 600 C. styrene isproduced in a yield of 40 mol percent.

Example 11 Isobutane is dehydrogenated to isobutylene employing acatalyst which is by weight 97 percent Fe O and 3 percent LiOH. 15 molsof steam, 1.0 mol of oxygen and .085 mol of bromine (fed as H'Br) areemployed per mol of isobutane. At a flow rate of 1 LHSV and a reactortemperature of 600 C. isobutylene is produced at a selectivity of 63percent.

Example 12 Example 11 is repeated substituting propane for isobutane toproduce propylene.

Example 13 Isopentane is dehydrogenated to isoprene and amylenes using acatalyst of =80 percent by weight NiCl and 20 percent KCl. 15 mols ofsteam are used, 1.5 mols of oxygen and 0.11 mol of bromine (fed as HBr)per mol of isopentane. At a flow of 0.5 LHSV and a reactor temperatureof 500 C. the selectivity is 68 percent.

Example 14 Propionitrile is dehydrogenated to acrylonitrile in a oneinch internal diameter reactor according to the general procedure above.Based on the propionitrile the molar ratio of oxygen is 1.0 and ofiodine (fed as HI) is 0.04. Helium is also present in the mixture in aratio of 15 mols per mol of propionitrile. The catalyst is a 90 weightpercent Fe O and Weight percent CaO. The flow rate of propionitrile is0.5 LHSV. At 675 C. the conversion is 77 percent, the selectivity is 76percent and the yield is 58 mol percent.

Examples to 21 A series of runs are made to demonstrate the inventionfor the dehydrogenation of n-butane. A Vycor reactor is used. The molarratio of reactants is 1.25 mol of oxygen, mols of helium and 0.08 mol ofBr per mol of butane. The flow rate is .2 LHSV.

sisting of n-butene, n-butane, isopentene, isopentane and mixturesthereof.

5. The method of claim 4 wherein the said temperature is at least 450 C.

6. The method of claim 4 wherein steam is employed in the said vaporphase in an amount of from 2 to mols of steam per mol of saidhydrocarbon.

7. The method of claim 4 wherein the oxygen is present in the amount ofgreater than 3.0 mols of oxygen per mol of said bromine and the saidbromine is present in an amount of from .001 to .09 mol of bromine permol of said hydrocarbon.

8. The method of claim 4 wherein the alkali and alkaline earth metalcompounds are present in an amount of from about .01 to 0.5 atom in thealkali or alkaline The process of this invention is particularlyapplicable to the dehydrogenation of hydrocarbons, includingdehydroisomeriZati-on and dehydrocyclization, to form a variety ofacyclic compounds, cycloaliphatic compounds, aromatic compounds andmixtures thereof. For example, 2-ethylhexene-1 may be converted to amixture of aromatic compounds such as toluene, ethyl benzene, p-xylene,o-xylene and styrene.

I claim:

1. The method for dehydrogenating organic compounds selected from thegroup consisting of hydrocarbons and nitriles having 2 to 20 carbonatoms to produce a dehydrogenated product having the same number ofcarbon atoms and the same structure with the exception of the removedhydrogen atoms which comprises heating in the vapor phase at atemperature of above 400 C. said organic compound having a I-II Illgroup with oxygen in a molar ratio of greater than onefourth mol ofoxygen per mol of said organic compound, bromine in an amount of lessthan 0.5 mol of bromine per mol of said organic compound, the ratio ofthe mols of said oxygen to the mols of said bromine being at least 2.5,the partial pressure of said organic compound being equivalent to lessthan one-half the total pressure in the presence of a catalystcomprising as its main active constituent (1) a compound selected fromthe group consisting of oxides, salts and hydroxides of alkali andalkaline earth metals and mixtures thereof, and (2) metals or compoundsthereof of Periodic Table Group VIIIb.

2. The method of claim 1 wherein the said organic compound is ahydrocarbon having from 2 to 12 carbon atoms.

3. The method of claim 1 wherein the said organic compound is an acyclicaliphatic hydrocarbon of 4 to 6 carbon atoms.

4. The method of claim 1 wherein the said organic compound is ahydrocarbon selected from the group conearth metal elements per atom ofthe metal elements of the said (2).

9. The method of claim 4 wherein the bromine is present in an amount ofno greater than 10 mol percent of the total gaseous mixture in thedehydrogenation zone.

10. A method for dehydrogenating hydrocarbons con taining 4 to 5 carbonatoms which comprises reacting in the vapor phase at a temperaturebetween 400 C. and about 750 C. an aliphatic hydrocarbon containing 4 to5 carbon atoms with oxygen in a molar ratio of about 0.4 mol to about 2mols of oxygen per mol of hydrocarbon, and above 0.001 mol to less than0.2 mol per mol of aliphatic hydrocarbon of bromine, at a partialpressure of said hydrocarbon of less than about one-third the totalpressure in the presence of a mixture of (l) a compound selected fromthe group consisting of alkali metal oxides, alkaline metal hydroxides,alkaline earth metal oxides and alkaline earth metal hydroxides, and (2)an inorganic metal compound of a Group VIIIb metal and mixtures thereof.

11. The method of claim 1 wherein the metal of said (2) comprises iron.

12. The method of claim 1 wherein the metals of the said (1) areselected from the group consisting of lithium, sodium, magnesium,potassium, calcium, strontium, barium and mixtures thereof.

13. The method of claim 1 wherein the metals of the said (1) and (2) arepresent as oxides, halides, or mixtures thereof.

14. The method of claim 10 wherein the said (2) comprises iron oxide.

References Cited by the Examiner UNITED STATES PATENTS 3,130,241 4/1964Baijle et al. 260677 3,207,806 9/1965 Bajars 260680 DELBERT E. GANTZ,Primary Examiner.

G. E. SCHMITKONS, Assistant Examiner.

1. THE METHOD FOR DEHYDROGENATING ORGANIC COMPOUNDS SELECTED FROM THEGROUP CONSISTING OF HYDROCARBONS AND NITRILES HAVING 2 TO 20 CARBONATOMS TO PRODUCE A DEHYDROGENATED PRODUCT HAVING THE SAME NUMBER OFCARBON ATOMS AND THE SAME STRUCTURE WITH THE EXCEPTION OF THE REMOVEDHYDROGEN ATOMS WHICH COMPRISES HEATING IN THE VAPOR PHASE AT ATEMPERATURE OF ABOVE 400*C. SAID ORGANIC COMPOUND HAVING A